Undoped semiconductor CdSe nanocrystal (NC) arrays have been found to be highly insulating (Ginger, D. S., et al., J. Appl. Phys. 87, p. 1361-1368, 2000; Morgan, N. Y., et al., Phys. Rev. B 66, 075339, 2002). Due to the nanometer size scale of the NCs, quantum confinement effects play a dominant role in their electronic properties. Individual CdSe NCs have discrete energy levels separated by 100 meV and charging energies ˜150 meV (Morgan et al.). CdSe quantum dots capped with ˜1-nm thick organic ligands act as tunnel barriers for charge transport between adjacent dots. Time-dependent transport phenomena, history effects and persistent photoconductivity in CdSe NC arrays have been observed (Ginger et al., Morgan et al., Woo, W., et al., Adv. Mater., 15, 1068, 2002; Drndic, M., et al., J. Appl. Phys. 92 (12), 7498, 2002). Proposed models to explain these effects include charge traps (Ginger, et al.,), the Coulomb glass [2,4] (Morgan, et al., and Drndic, et al.), and Levy statistics (Novikov, D. S., et al., Cond. Mat. Phys., preprint, 0307031, 2003).
U.S. Pat. App. Pub. No. 2004/0256662 to Black et al. pertains to nonvolatile memory device using semiconductor nanocrystals and method of forming same. U.S. Pat. App. Pub. No. 2004/0043583 to Rao, et al. pertains to a method of forming nanocrystals in a memory device. U.S. Pat. App. Pub. No. 2002/0163830 to Bulovic et al. pertains to molecular memory devices. Further improvements in memory devices and recordable media are needed.